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Nocturnal Animals

Beavers Gathering & Storing Winter Food Supply

10-15-13  beaver winter food supply pile 292(Part 3 of 3 Beaver posts)
In the fall, beavers spend weeks cutting, transporting and piling sticks and branches whose bark, twigs and leaves will hopefully provide them with sustenance through the winter. With no access to land once ice forms, beavers rely on the food that they have had the foresight to store on the bottom of the pond in the fall, as close to the main entrance to their lodge as possible. Initially the beavers dive down and stick the butt end of the branches into the mud. Once anchored, these branches form the base of a growing pile which often sticks out above the surface of the pond. (The portion of the pile above the water is not accessible to the beavers once the pond freezes.) According to beaver biologist Leonard Lee Rue, a beaver colony needs to store between 1,500 and 2,500 pounds of edible bark, twigs and leaves (this weight doesn’t include the wood, as they don’t eat wood) if it is to sustain them through the winter. As one would suspect, southern beavers do not need nor make winter food supply piles.

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Beavers Refurbishing Lodge

10-14-13 refurbished beaver lodge 248This is the time of year when the industriousness of beavers can determine whether or not they survive through the winter. There are three major tasks for a beaver colony to tend to in the fall: refurbishing their lodge; strengthening and repairing their dam; and cutting and storing their winter food supply. They tend to perform these tasks in this sequence, tackling the lodge first. If the water level is high, the beavers will raise the floor of the lodge and the roof of the sleeping chamber. Every fall they add new material to the exterior of the lodge to strengthen the entire structure – typically sticks intertwined that create walls two feet thick or more. At this point the beavers coat the lodge with mud that they dredge up from around the base of the lodge (which greatly increases the depth of the water near the lodge). The apex of the lodge is not coated, allowing fresh air to filter down into the sleeping chamber. Once cold weather arrives, the mud hardens to the consistency of concrete, making the lodge is impenetrable to predators that can approach the lodge once the pond freezes. (In photo, note the fresh eastern hemlock branches and mud that have recently been added to the lodge.)

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.


Mutual Grooming

8-1-13 beavers grooming each other IMG_2714Beavers spend a great deal of time tending to their coats, grooming several hours a day throughout the year. Grooming consists of removing sticks and debris that have become embedded in their fur, as well as applying oil from their anal glands to waterproof their fur. Waterproofing is essential, as it prevents the cold water from penetrating their fur. Typically they sit with their tail between their hind legs, stretched out in front of them, with their anal glands exposed. Beavers procure the oil with their front feet, and use all four feet to comb it through their fur. The two inside nails on both of their hind feet are split, increasing the efficiency with which they can apply the oil. Sometimes two beavers will groom each other, engaging in “mutual grooming.” The male and his offspring begin to groom each other when the kits are only two weeks old, yearlings and kits from three weeks on, and the mother and kits when the young are four weeks old. Mutual grooming continues as long as they are a family unit. ( I am humbled by the response to yesterday’s post. You will each be hearing from me soon. )


Owl Ears

3-26-13 barred owl ear IMG_7161It’s well known that owls have an acute sense of hearing — some species, such as the barn owl, hunt nocturnally by sound alone. An owl’s asymmetrically-placed ears are located beneath the feathers at the edge of its facial discs. This placement, along with the shape of the external ear canals, is thought to contribute to an owl’s keen ability to locate sound. The flesh-colored fold of skin that you see in front of this barred owl’s ear is movable, and reflects and concentrates sound waves coming from behind the bird.


Coyotes and Beavers

3-12-13 coyote & beaver lodge2 IMG_6223A study of coyote prey (through stomach contents) in the Adirondack Mountains of New York revealed that beavers were second only to white-tailed deer. This photograph shows that, possibly for the last time this winter, a coyote recently took advantage of a still-frozen-but-fast-thawing pond by walking across it in an attempt to reach an active beaver lodge. Once there the coyote attempted to dig into it in order to reach the inhabitants. A hard, two-to three-foot-thick wall of frozen mud, logs and sticks kept the beavers well protected, as it was designed to.


Raccoons Up & About

3-7-13 raccoon IMG_2452 copyWhile we don’t see raccoons much in the winter, it isn’t because they’ve been hibernating. Rather, during cold spells, they seek shelter, often in hollow trees, where they remain for up to a month at a time in a fairly lethargic state (but not true hibernation). If the temperature at night rises above freezing, raccoons are out foraging. Lately their tracks have been very evident, signaling that their nights of inactivity are coming to an end. There isn’t much food for them to find this time of year, so for the most part they are living off the fat that they accumulated last fall.


Porcupines Tapping Out

porcupine tap IMG_3494At least one porcupine got a jump on humans this sugaring season. A porcupine eats outer tree bark in order to access the phloem (layer of inner bark cells that transport nutrients) and cambium (produces phloem and xylem cells) layers of a tree, its primary winter diet. In eating these layers, the porcupine unintentionally cuts into the xylem, or sapwood, where water and dissolved minerals (sap) are transported between the roots and crown of the tree. Unintentionally, porcupines tap the trees whose phloem and cambium they eat. In this case, the weather had warmed up enough to cause pressure in the tree, which in turn caused the sugar maple’s sap to flow just as a hungry porcupine happened along. Soon thereafter, the temperature dropped, causing the sap to freeze, forming icicles. While they looked good enough to sample, one whiff of them told me that sap was not their sole ingredient! (They were located beneath the porcupine’s den in a hollow tree, from which urine flows freely.)


Striped Skunk Mating Season

2-18-13 striped skunk tracks IMG_3244Striped skunks are nocturnal and, for the most part, semi-dormant in the winter, especially during cold spells. The females often gather in communal dens in groups as large as 15. Come mid-February the polygamous males become very active, searching far and wide for mates. Although the mating season doesn’t peak until mid-March, tracks throughout woods and fields confirm that the breeding season is in full swing. During a typical night a skunk may cover ¼ to ½ a square mile, but during the breeding season, this increases to 4 or 5 square miles.


Porcupine Trail

porcupine trail IMG_0059It’s fairly obvious when there are active porcupines in the woods, as they leave all kinds of signs. The females, who often spend the day in a hollow tree or rock den, come out at night to eat (males often spend several days up in a tree), and leave very pronounced 6” – 9” trails back and forth to their feeding trees. Along this trail, in addition to an occasional quill, there are often pellets of scat as well as urine, which both your eyes and your nose can detect. Porcupines discard the tips of hemlock branches when they’re through eating the tender buds and leaves up in the canopy, and consequently the ground under a feeding tree is often littered with “nip twigs.”


Raccoon Tracks

12-6-12 raccoon tracks IMG_0046The relatively warm, wet start to winter has provided us with the opportunity to see riverside tracks that might otherwise not be evident.  Raccoons are known for their ability to go anywhere and get into anything and the reason for this dexterity is revealed in their tracks.  Both front and hind feet have five long toes.  Although the “thumb” is not opposable, it is long enough to grasp things. Because of this dexterity, raccoon tracks can vary widely.   In mud and snow, they often resemble small human hands.  Typically the toes of the front feet are more splayed out than those of the hind feet.


A Great Christmas Present!

If you’re looking for a present for someone that will be used year round, year after year, Naturally Curious may just fit the bill.  A relative, a friend, your child’s school teacher – it’s the gift that keeps on giving to both young and old!

One reader wrote, “This is a unique book as far as I know. I have several naturalists’ books covering Vermont and the Northeast, and have seen nothing of this breadth, covered to this depth. So much interesting information about birds, amphibians, mammals, insects, plants. This would be useful to those in the mid-Atlantic, New York, and even wider geographic regions. The author gives a month-by-month look at what’s going on in the natural world, and so much of the information would simply be moved forward or back a month in other regions, but would still be relevant because of the wide overlap of species. Very readable. Couldn’t put it down. I consider myself pretty knowledgeable about the natural world, but there was much that was new to me in this book. I would have loved to have this to use as a text when I was teaching. Suitable for a wide range of ages.”

In a recent email to me a parent wrote, “Naturally Curious is our five year old’s unqualified f-a-v-o-r-I-t-e  book. He spends hours regularly returning to it to study it’s vivid pictures and have us read to him about all the different creatures. It is a ‘must have’ for any family with children living in New England…or for anyone that simply shares a love of the outdoors.”

I am a firm believer in fostering a love of nature in young children – the younger the better — but I admit that when I wrote Naturally Curious, I was writing it with adults in mind. It delights me no end to know that children don’t even need a grown-up middleman to enjoy it!


Flying Squirrels Visiting Bird Feeders

Are you finding that the amount of seed in your bird feeders drops precipitously after dark?  Those of us in black bear country are advised to bring feeders in at night so as not to attract bears, but occasionally several hours of darkness have passed before I remember to do so.  When that happens, the feeders inevitably need filling.  What stealthy critter is visiting once the sun goes down?  Very possibly, flying squirrels are the culprits.  These nocturnal rodents can glide as far as 295 feet from tree to tree, or tree to ground.  They stretch their legs out and direct their glide by controlling the position of the flap of skin (patagium) that extends from the outside of the wrist on the front leg to the ankle of the hind leg on both sides of their body.  Their broad, flattened tail acts as a parachute, rudder, stabilizer and brake during the glide.  Feeders are rarely far enough from a tree to necessitate a glide – a short leap does the trick.  If you feed birds, try shining a light on your feeders after the sun goes down.  You may very well be treated to the sight of several flying squirrels helping themselves to your sunflower seeds and suet.


Gray Fox

The gray fox (Urocyon cinereoargenteus), although peppery gray on top, has reddish-brown fur on its sides, chest and the back of its head, which explains why it is sometimes mistaken for a red fox.  Its tail has a distinct black stripe along the top, and a black tip (red fox tails have a white tip).  Gray foxes are shier and more secretive than red foxes, and are seen much less frequently.  Probably the characteristic for which the gray fox is best known is its ability to climb trees.  The claws of the gray fox’s front feet are more curved than those of the red fox – an adaptation for climbing. They are very skillful climbers, and once a gray fox has shinnied up the trunk of a tree to a limb, it will jump from branch to branch in pursuit of prey, such as squirrels.


Camel Crickets

Camel crickets are named for their humpback appearance. We don’t often see these wingless insects, for they prefer dark, damp habitats such as under stones and logs, where we don’t often look. However, when there are extreme weather conditions, such as excessive rainfall or the extended periods of hot, dry weather which we have experienced this summer, camel crickets are attracted to damp cellars and crawl spaces, giving us an opportunity to admire their impressive legs. Often mistaken for spiders, camel crickets do have long legs, but only six, not eight, of them. Their two hind legs are obviously longer and stronger than the other four, and enable this cricket to jump three feet high, a skill they use for defense against predators. A local blog reader reports that three nights in a row (camel crickets are nocturnal), due to the force of its jump, a camel cricket tripped a small have-a-heart trap set in their cellar for mice. (Thanks to the Choukas for photo op.)


Signs of Striped Skunks

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If you are finding small, conical pits in your lawn, you probably have a striped skunk to thank for reducing your grub population.  During the spring and summer, invertebrates make up a large percentage of this nocturnal omnivore’s diet.  With the help of their well-developed sense of smell and their long nails (which make them excellent diggers), they locate, gain access to and consume subterranean insect larvae with relative ease.   Another sign of skunk activity, in addition to lawn divots, are the excavated ground nests of yellowjackets.  If they’ve met with success, skunks will often leave sections of empty, paper cells scattered about the nest site.  Apparently, even though yellowjackets can sting multiple times, they’re not very effective at discouraging foraging skunks.  Should you be so inclined, a close examination of skunk scat will reveal bits of insect exoskeletons, as well as the bones and hair of small rodents.  The pictured scat (next to the divot) contained, in addition to insect parts, the fur of another nocturnal animal, a flying squirrel.  (Thanks to Emily and Joe Silver for photo op.)


Barred Owl Diet

This is pure conjecture, but here goes. Barred Owls are known to consume small mammals, birds, reptiles, amphibians, fish and invertebrates. I have repeatedly encountered a Barred Owl lately near a pool of water in a brook that has all but dried up. Fish have become trapped in this pool due to the dryness of the summer, and are easy pickings for predators. Even though studies have shown that fish are a very small percentage of a Barred Owl’s diet (2.5% in owls from New Jersey, New York and Connecticut during the breeding season), I am betting that the owl that I flushed yesterday that was perched right next to the isolated pool in the brook was spending the day (and night?) at his favorite fishing hole. Three times it took off from its perch as I approached, but only flew a few feet away each time. Perhaps fish or frogs kept it from disappearing further into the woods.


Great Horned Owl Fledglings

Hardy birds that they are, Great Horned Owls are one of the earliest nesting birds — you can find them on nests in January, February and March, even in northern New England. Eggs are incubated for about a month, typically in March or April with young usually hatching in May or June. The nestlings remain in the nest for six or seven weeks before fledging. Unable to fly until they’re ten or twelve weeks old, the fledglings follow their parents around and continue to be fed and cared for by them until the fall. These two fledglings were sticking close together as they made their raspy begging calls from high in a white pine. Both their calls and the down that was visible on their heads told me that they were this year’s young.


Porcupines and Hollow Tree Dens

Porcupines leave plenty of signs where they have eaten the inner bark, or cambium layer, of a tree. Bark is missing on the trunk of the tree, leaving fresh, yellow wood exposed, which often bears incisor marks.  An observation I have made over the years is that porcupines often de-bark around or near their hollow tree dens.  Typically, if a tree den is used year after year, they gnaw off bark each year, sometimes eating the old, scarred portion which, due to previous chewing, lacks cambium cells. This has led me to wonder whether fresh de-barking in the vicinity of their tree den entrance might have more, or as much, to do with a  porcupine’s staking out a claim on that tree than with its sustenance.  I have never come across any research that even mentions this phenomenon, and would welcome feedback from anyone who has.


Flying Squirrels

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We have two species of flying squirrels in most of New England, the Southern (Glaucomys volans) and Northern (Glaucomys sabrinus), which is larger and usually more brownish than its cousin.  One could deduce that these gentle rodents are nocturnal just by looking at the size of their luminous eyes.  Because they feed at night, we don’t set eyes on them very often, except for an occasional lucky glance at the bird feeder before heading to bed. If we did observe them more often, we would marvel at their stretching their legs out, extending a flap of skin that runs from their front legs to their hind legs, and effortlessly soaring from one tree to another — as far as 150 feet horizontally from a height of 60 feet.  One documented sighting that I would love to observe is a female carrying young while gliding!


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